1. Field of the Invention
The present invention relates to a data transfer apparatus for performing fast data transfer between a first storage medium such as a hard disk and a second storage medium and a method of the same and to a data input and output controlling apparatus and a method of the same.
2. Description of the Related Art
In recent years, hard disks, which are non-linear access storage media, have spread in use in place of magnetic tape as the media for storing audio and/or video signals etc. This is because hard disk drives enable fast access and fast transfer of data.
In "jog-shuttling" and other fast reproduction modes of video tape recorders etc., since data is reproduced only at certain intervals, the amount of the data transferred is the same as that during standard speed reproduction. "Fast transfer", on the other hand, is a function for transferring the same data as that of the standard speed reproduction at a faster rate. In the case of double speed transfer, twice the amount of data compared with that of the standard speed transfer is transferred per unit time. In this fast transfer, it is important to be able to copy the data at a high speed.
With hard disks, however, the access speed differs according to where on the disk the data is stored. Further, with hard disks, there are two types of error: recoverable error, where the stored data can be read by accessing the same location several times, and unrecoverable error, where the stored data cannot be read even by accessing the location several times. Further the time for transferring the data sometimes changes due to rotation waiting time, temperature compensation, etc.
Therefore in the related art, when for example transferring audio and/or video data between hard disks, the data transfer rate was set to the slowest expected transfer rate so as to enable fluctuations in the data transfer rate of the hard disk drive to be suitably absorbed by a limited storage capacity buffer memory. That is, the fluctuations of the transfer rate were only temporarily absorbed by the buffer memory based on the storage capacity of the buffer memory, so that it was necessary to set the rate of transfer to the hard disks somewhat slower than the actual performance of the hard disk drive so as not to overload the buffer memory.
Since, as described above, the data transfer rate between hard disks was set slower than the actual performance of the hard disk drive, it was necessary to use a hard disk drive offering a higher transfer rate than required in order to achieve the required transfer rate. This complicated the apparatus and made it more expensive.
A similar problem occurs when transferring data between magnetic tape and a hard disk.